Effects of complex dopants on the microstructure and dielectric properties of BCTZ ceramics

A new route was developed to produce high-performance nonreducible (Ba,Ca)(Ti,Zr)O₃ (BCTZ) ceramics, in which sol-gel derived complex dopants were applied to ultrafine (Ba_0.97Ca_0.03)_1.001(T{i}_0.80Zr_0.20)O₃ powders. The effect of calcination temperature on the complex dopants, as well as the effect of complex dopants on the BCTZ ceramics was investigated. The micro-strain, Curie point, dielectric loss and maximum dielectric constant at the Curie point of the resulting BCTZ ceramics all decrease with increasing mean crystallite size as the calcination temperature of the complex dopants increases. It is suggested that the above results are presumably due to the downsizing of the agglomerates of the complex dopants during calcination. The effectiveness of the present route to improve the dielectric constant and loss of the BCTZ ceramics simultaneously has been verified in comparison to the conventional mixed oxide route. This new route is very promising for practical use in Ni-electrode multi-layer ceramic capacitors (Ni-MLCCs) with large capacitance.